WVN is a cause of aseptic meningitis that has recently spread across the U.S. to Canada. Usually, west nile virus causes a self-limited (gets better on its own, without treatment) meningitis. Infrequently, it causes a more severe illness, which may include encephalitis (inflammation in the actual brain tissue) or paralysis similar to that seen in polio. Guillain Barre syndrome (GBS) and its variants can present similarly. These severe forms usually occur in elderly people or people with lowered immunity. In this case, the meningitis may mimic the signs and symptoms of hepatic encephalopathy, or hepatic coma. Predisposing factors in hepatic encephalopathy include a history of blood in urine or stool, opiate use, infection, GI bleeding, dehydration or electrolyte abnormalities. Additionally, hepatic encephalopathy can also occur with non-cirrhotic forms of portal hypertension. – hepatic encephalopathy – docstoc

Classically, West Nile virus infection is suspected in persons with unexplained encephalitis and meningitis. Brainstem encephalitis, cerebellitis, movement disorders, cranial neuropathies, polyneuropathy/radiculopathy, chorioretinitis and optic neuritis are also recognized WNV neurological presentations. Disease attributed to WNV presents in one of four clinical fashions: West Nile fever, meningoencephalitis, a flaccid paralysis (polio-like syndrome), and a Parkinson-like syndrome.

West Nile virus transmission occurs mostly during warm weather, when mosquito populations are active. Peak transmission of the WNV occurs between July and October, but cases have occurred as early as April. Further, numerous cases of WNV infection via transfusion of blood products (from asymptomatic, viremic donors) have been reported. Most people infected by West Nile Virus do not get sick. A small number of people may experience mild fever, headaches, muscle weakness and a stiff neck. In rare cases, the symptoms may progress to serious illness involving inflammation of the brain (encephalitis) or the lining of the brain and spinal cord (meningitis).

WNV has been associated with severe cerebral abnormalities and intracranial calcifications. Treatment is mainly supportive, and no antiviral medications have any proven benefit in the management of WNV. Severe WNV infection can mimic GBS but is differentiated by fever; encephalopathy; predominantly proximal, asymmetric weakness; axonal pathology on nerve conduction studies and cerebrospinal fluid variables.
West Nile virus encephalitis mimicking central nervous system metastases from small cell lung cancer is reported in the literature. The American Journal of Medicine , Volume 115 , Issue 7, Pages 594 – 595 A . Jeyakumar.

During the 1999 New York City West Nile virus (WNV) outbreak, 4 patients with profound muscle weakness, attributed to Guillain-Barre syndrome, were autopsied. These cases were the first deaths caused by WNV.
GBS can also be mistaken for botulism, lyme disease, poisonous shellfish, diptheria, sarcoidosis, even rabies. Disorders that can mimic Guillain-Barre syndrome include tick paralysis, toxic neuropathies, porphyria, transverse myelitis, acute spinal cord compression and poliomyelitis. Infection can even mimic Guillain-Barré syndrome. Even MS is related in a fashion similar to axonal and demyelinating Guillain-Barré syndrome. MS and GBS are autoimmune inflammatory diseases. These and other conditions that may mimic the Guillain-Barre syndrome need to be ruled out. The clinical diagnosis of GBS needs to be confirmed by cerebrospinal fluid analysis and nerve conduction studies. Lumbar puncture is indicated in every case of suspected GBS.
CAVEAT: West Nile virus (WNV) infection is a potentially fatal disease, with meningoencephalitis being its most common neurological manifestation.

Evidence of West Nile encephalitis virus (polio-like) infection has been documented in most states of the continental U.S. and Canada within a short period of its first introduction in 1999. Health care providers are mostly aware of the usual presentations of this disease, eg, “aseptic meningitis, encephalitis and Guillain-Barre syndrome”, suggesting a shared mechanism.

For the record, West Nile virus (WNV) can cause severe, potentially fatal neurological illnesses, which include encephalitis, meningitis, Guillain Barre syndrome, and anterior myelitis. WNV season: May through October.

Know that polio has not been eradicated by vaccination, it is lurking behind a redefinition and new diagnostic names like WNV, viral or aseptic meningitis, and Guillain Barre Syndrome. – Hiding Polio

The signs and symptoms of Guillain Barre Syndrome (GBS) are almost indistinguishable from that of the West Nile Virus (WNV) and visa-versa, as both share a propensity for presenting similarly with muscle weakness and flaccid paralysis. In fact, GBS and WNV ofter mimic each other. West Nile Virus begins like the flu, and so does GBS.